Treatment fluids can be employed in a variety of subterranean operations. As used herein the terms “treatment,” “treating,” other grammatical equivalents thereof refer to any subterranean operation that uses a fluid in conjunction with performing a desired function and/or for achieving a desired purpose. The terms “treatment,” “treating,” and other grammatical equivalents thereof do not imply any particular action by the fluid or any component thereof. Illustrative subterranean operations that can be performed using treatment fluids may include, for example, drilling operations, cementing operations, fracturing operations, sand control operations, gravel packing operations, acidizing operations, conformance control operations, fluid diversion operations, fluid blocking operations, and the like.
While drilling oil and gas wells, a drilling fluid is circulated through a drill bit in a well bore and then back to the earth surface, thereby removing cuttings from the well bore. The drilling fluid is then often reconditioned and reused. In the well bore, the drilling fluid maintains a predetermined hydrostatic pressure. However, when the drill bit encounters certain unfavorable subterranean zones, the hydrostatic pressure is compromised, resulting in what is commonly known as “lost circulation.” For example, lost circulation occurs when the drill bit encounters comparatively low pressure subterranean zones, such as vugs, fractures, and other thief zones. Similarly, encountering comparatively high pressure subterranean zones results in crossflows or underground blow-outs, and subsequently lost circulation.
Treatment for fluid-loss control can be used during any of drilling, completion, and intervention operations. During completion or intervention, stimulation is a type of treatment performed to enhance or restore the productivity of oil or gas from a well. Stimulation treatments fall into two main groups: hydraulic fracturing and matrix treatments. Fracturing treatments are performed above the fracture pressure of the subterranean formation to create or extend a highly permeable flow path between the formation and the wellbore. Matrix treatments are performed below the fracture pressure of the formation. Other types of completion or intervention treatments can include, for example, gravel packing, consolidation, and controlling excessive water production, and controlling sand or fines production. Still other types of completion or intervention treatments include, but are not limited to, damage removal, formation isolation, wellbore cleanout, scale removal, and scale control.
Different types of “lost circulation materials” (hereinafter “LCMs”) may be used. These include ground marble, graphitic based materials, ground nut shells, ground almond shells, cedar fiber, mineral and other types of polymeric fibers, carbon fibers, cellulose, chitin, polymers, and nano materials. Polymers have been used in certain drilling applications, such as additives to drilling fluids. The properties or shapes of materials constructed of the polymers may be changed by altering the treatment fluid properties or the physical conditions such as temperatures. Cellulose and chitin sheets have been coated or partially coated with polymers that deform when subjected to various conditions. However, typically the cellulose and chitin sheets may dissolve in the various types of drilling fluids. Additionally, the substrates and coating polymers are used in a way that only allows them to change their shape only once, and the shape changing is often triggered by a change in fluid properties, thereby requiring different polymer materials for different treatment fluids. Further, the polymers are not able to revert back to their original state if required, particularly if the substrate structure has dissolved in the fluid. At times, conventional lost circulation materials do not work as efficiently as needed. And hence there is always a need to supplement the LCMs with novel or new materials to enhance their performance. Accordingly, there is a need for a shape changing polymer structure that may be used in a variety of different types of drilling fluids, and after being deployed and activated in a well, has the ability to revert back to its original shape.